Contrast media in MR arthrography of the glenohumeral joint: intra ...

Eur. Radiol. 7, 498–502 (1997)  Springer-Verlag 1997

European Radiology

Original article Contrast media in MR arthrography of the glenohumeral joint: intra-articular gadopentetate vs saline: preliminary results M. Zanetti, J. Hodler Department of Radiology, University of Zurich, Orthopedic University Clinic Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland Received 24 May 1996; Accepted 30 August 1996

Abstract. The purpose of this investigation was to compare gadopentetate and saline as contrast media in MR arthrograms of the glenohumeral joint. In 60 consecutive patients MR arthrograms with either gadopentetate (n = 26) or saline (n = 34) were performed. After injection of gadopentate, 3D gradientecho (GE) images were obtained (TR 32 ms, TE 10 ms, flip angle 40 °). With saline, double-echo steady-state images (heavily T2-weighted 3D GE images) were obtained (TR 40 ms, TE 9/45 ms, flip angle 40 °). In the last 14 of these patients T2-weighted turbo spin-echo (SE) images were added (TR 2900 ms, TE 96 ms). Contrast-to-noise ratios standardized for imaging times proved to be superior for the gadolinium arthrograms compared with GE and SE saline arthrograms (intra-articular fluid vs subacromial fat: p = 0.0001 and 0.0008; intra-articular fluid vs supraspinatus tendon: p = 0.0001 and 0.046). Using a qualitative scoring system gadolinium arthrograms were superior to saline arthrograms (p < 0.0001 and p < 0.0001). Saline arthrograms in combination with GE and SE sequences are inferior to gadopentetate arthrograms with GE sequences. Key words: MR arthrography – Contrast media – MRI – Glenohumeral joint – Rotator cuff

Introduction Magnetic resonance arthrography of the shoulder has been advocated by several authors [1–5]. The MR arthrography technique may add important information about the labrum and the capsule. With regard to the rotator cuff, differential diagnosis between partial rotator cuff tears and tendinopathy and small full-thickness tears, respectively, may be facilitated. As indicated in a previous paper [6], gadolinium-containing contrast meCorrespondence to: M. Zanetti

dia such as gadopentetate (Magnevist, Schering, Berlin, Germany) or gadoterate (Dotarem, Guerbet, Aulnaysous-Bois, France) seem to provide superior image contrast when compared with joint fluid, saline or iodinecontaining contrast media. However, they are not registered for intra-articular use in the United States and other countries, and there is an increased interest in using alternate contrast media. The purpose of this investigation was to compare quantitatively and qualitatively MR arthrography of the glenohumeral joint using either saline or gadopentetate with gradient-echo (GE) and turbo spin-echo (SE) imaging. Patients and methods Performing MR arthrograms has been approved by our hospital’s ethics committee. A total of 60 consecutive patients referred for MR arthrography of the glenohumeral joint were included in this investigation. The patients were submitted to either a saline or gadolinium arthrogram based on their hospital number. This is a sixdigit number given to the patient by the reception desk during his/her first appointment. The numbers are attributed in a consecutive manner. No bias is introduced by the type of appointment (e. g. inpatient vs outpatient, region involved). In 34 patients (age 19–75 years, mean age 45.7 years) with even numbers a saline arthrogram was performed, and in 26 patients (age 16–74 years, mean age 42.2 years) with odd numbers a gadolinium arthrogram was performed. Sixteen patients were women, and 44 were men. The two groups were not statistically different with regard to gender (unpaired two-tailed t test; p = 0.23) or with regard to age (unpaired two-tailed t -test; p = 0.08). Diagnostic advantages and possible side effects of MR arthrograms were explained to the patient before performing the examination.

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Fig. 1. A 3D fast imaging with steadystate precession (FISP) arthrogram (TR 32 ms, TE 10 ms, flip angle 40 °). Regions of interest within axillary recess (1) and subacromial fat (2)

1

2

MR imaging The joint was punctured under fluoroscopic control using local anaesthesia. The intra-articular position of the needle tip was confirmed by injection of 2 ml of sodium meglumine ioxaglate (Hexabrix 320, Guerbet, Aulnaysous-Bois, France) Between 10 and 15 ml of diluted gadopentetate was then injected. Concentration was 0.2 mmol/ml. The exact volume of injected gadopentetate depended on the presence of a rotator cuff tear and/or the capsule volume as estimated during the injection of ioxaglate. Angled coronal and axial images were then obtained using a 1.0-T scanner and a dedicated receiveonly shoulder coil (Siemens Impact, Siemens Medical Systems, Erlangen, Germany). Three-dimensional fast imaging with steady-state precession (FISP) images were obtained in the gadolinium arthrograms. The TR was 32 ms, TE 10 ms and flip angle 40 °. A 50-mm slab of 16 slices was obtained. Slice thickness was 3.1 mm. Field of view (FOV) was 180 mm with an image matrix of 192 × 256 and one excitation. Imaging time was 1 min, 40 s. For the saline arthrograms a 3D double-echo steady-state (DESS) sequences was obtained. The TR was 30 ms, TE 9/45 ms and flip angle 40 °. Slice thickness was 3.1 mm (16 images, 50-mm slab). The FOV was 180 mm, image matrix was 192 × 256 and two excitations were used. Imaging time was 3 min, 6 s. The 3D-DESS sequence is a combination of a FISP and a PSIF (reverse FISP) sequence. The PSIF sequences produces heavily T2-weighted images due to long TEs. Because the echo originates from the previous excitation, TE is nearly double TR. Both types of images are obtained during acquisition and are added into one DESS image. The DESS sequence permits to perform 3D imaging with T2-weighting. The 3D-DESS imaging is recommended by the manufacturer for imaging in orthopaedic indications and has been routinely used in our institution mainly for knee joints with good results. Using the DESS sequence hyaline cartilage has intermediate signal intensity, and joint fluid is hyperintense (see Fig. 5). Because the 3D-DESS saline arthrograms proved to be inferior qualitatively in some patients, T2-weighted turbo SE images were obtained in addition in the last 14 of the 34 saline arthrograms (TR 2900 ms, TE 96 ms, number of echos per echo train: 7, slice thickness

Fig. 2. A 3D-FISP arthrogram (TR 32 ms, TE 10 ms, flip angle 40 °). Signal intensity profile of distal supraspinatus

3.0 mm, 180 mm FOV, image matrix of 192 × 256, four excitations and imaging time of 5 min, 32 sec). Quantitative evaluation For quantitative assessment, the angled coronal image closest to the centre of the humeral head was chosen. Signal intensities (SI) were measured using a circular region of interest (ROI) within the axillary recess and the subacromial fat (Fig. 1). Minimum SI within the supraspinatus was determined by using the SI profile obtained from the major tuberosity to the musculoskeletal junction (Fig. 2). Background noise was determined by obtaining the standard deviation (SD) of SIs within a circular ROI placed outside the body. Contrast-to-noise ratios (CNR) were calculated for contrast medium in the axillary recess vs subacromial fat and the zone of lowest SI of the supraspinatus tendon by dividing SI differences by background noise. Standardized CNR were then obtained by multiplying image CNR with 10/square root of imaging time (measured in seconds). The standardized CNRs were compared by using either a two-sided paired (3DDESS vs fast SE) or a two-sided unpaired (3D-DESS and SE vs 3D-FISP) t -test. The results were considered to be statistically significant at the 5 % level. The pulse sequences used in the present investigation have been optimized for imaging in the presence of intraarticular of saline gadopentetate. In order to assess a possible bias CNR were calculated in an additional group of 20 consecutive patients in structures not enhanced by intraarticular contrast media (minimum signal intensity of the supraspinatus tendon and subacromial fat). Qualitative evaluation Qualitative scoring was performed using the same angled coronal image closest to the centre of the humeral head. Delineation of the rotator cuff was graded as 3 when the entire undersurface was covered by contrast (Figs. 3 and 4 a), as 2, when two thirds or more of the undersurface was covered, as 1, when one to two thirds were covered, and 0 when less than one third was covered (Figs. 4 b and 5). If delineation of the inferior sur-

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3

4a

4b

5

6a

6b

Fig. 3. A 3D-FISP arthrogram (TR 32 ms, TE 10 ms, flip angle 40 °). Complete delineation of undersurface of supraspinatus and undersurface of superior labrum (arrows) by intra-articular gadopentetate. During qualitative evaluation the borders between intra-articular contrast medium and surrounding structures were considered to be completely sharp in this patient. No motion artefacts are visible in this image Fig. 4. a A 3D double-echo steady-state (DESS) arthrogram (TR 30 ms, TE 9/45 ms, flip angle 40 °). Complete delineation of undersurface of supraspinatus by intra-artericular saline. Small erosion arrow close to the insertion site of the supraspinatus into the major tuberosity. b Turbo spin-echo image (TR 2900 ms, TE 96 ms). Same patient as in Fig. 4 a. Less than one third of supraspinatus delineated by saline Fig. 5. A 3D-DESS arthrogram (TR 30 ms, TE 9/45 ms, flip angle 40 °). Less than one third of the undersurface of the supraspinatus is delineated by intra-articular saline (arrowheads). Moreover, the borders between intra-articular saline and surrounding structures were considered to demonstrate significant blurring within the glenohumeral joint space (small arrows). Artefact is visible in axillary recess, consisting of central hypointensity within otherwise hyperintense saline (large arrow) Fig. 6. a Turbo spin-echo image (TR 2900 ms, TE 96 ms). Severe motion artefacts are present throughout the image. b A 3DDESS arthrogram (TR 30 ms, TE 9 ms, flip angle 40 °). Image corresponds to Fig. 6 a. No motion artefacts are visible

face of the superior labrum was complete; it was graded as 1 (Fig. 3), and 0 when not complete. The borders between the joint capsule and intra-articular contrast medium were graded as 3 when perfectly sharp (Fig. 3), as 2 in slight blurring (probably no interference with diag-

nosis), as 1 in significant blurring (Fig. 5; interference with diagnosis possible), and as 0 in severe blurring (interference with diagnosis probable). Motion artefacts were graded as 3 when no artefacts were present (Figs. 3 and 6 b), as 2 in minimal artefacts (probably no interference with diagnosis), as 1 in significant artefacts (interference with diagnosis possible), and as 0 in borderline examinations (interference with diagnosis probable; Fig. 6 a). These gradings and their sum were compared using a Mann-Whitney U-test for comparison of nonpaired measurements (DESS and SE vs FISP) and the Wilcoxon signed-rank test for the paired measurements (DESS and SE). Results Quantitative score Mean standardized CNR and their SDs for all three sequences employed are shown in Table 1, and results of the corresponding t -tests in Table 2. Standardized CNR for intra-articular contrast medium vs subacromial fat were highest for the FISP images and lower for the SE and DESS images. The differences of standardized CNR between FISP and the two other types of MR arthrograms were highly significant. No statistically significant difference of standardized CNR was found between the SE and DESS arthrograms. Standardized CNR for intra-articular contrast vs rotator cuff were again highest for the FISP arthrograms.

M. Zanetti and J. Hodler: MR arthrography: gadolinium vs saline Table 1. Quantitative evaluation in studies with intra-articular contrast media: means and standard deviations. CNR standardized contrast-to-noise ratio; fat CNR intra-articular contrast vs subacromial fat; rc CNR intra-articular contrast vs rotator cuff; DESS double-echo steady-state; FISP fast imaging with steady-state precession; SE turbo spin-echo; SD standard deviation FISP DESS SE

N

CNR fat (SD)

CNR rc (SD)

26 3 14

23.4 (14.6) 11.3 (7.5) 7.9 (8.6)

37.5 (24.2) 7.1 (7.3) 22.9 (14.5)

Table 2. Quantitative evaluation in studies with intra-articular contrast media: t -tests p for two-tailed t -test (p for non-standardized CNR) DESS vs FISPa SE vs FISPa DESS vs SEb a b

CNR fat

CNR rc

0.0001 (0.016) 0.0008 (0.62) 0.18 (0.67)

0.0001 (< 0.0001) 0.046 (0.077) 0.0003 (0.0001)

Unpaired t -test paired t -test

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grams, but a significant difference in SE arthrograms (with higher CNRs) vs FISP and DESS arthrograms. Qualitative scores The results of the qualitative scoring are shown in Table 5, and the results of statistical comparison in Table 6. With regard to rotator cuff delineation, the highest score was found for the FISP arthrograms followed by DESS and SE arthrograms. The differences were statistically significant between the FISP and the two other sequences, but not between SE and DESS images. With regard to delination of the labrum and image sharpness, no statistically significant differences were found between the three sequences. Spin-echo images proved to be more prone to motion artefacts than both other image types. For the total score FISP arthrograms were shown to be superior to the SE arthrograms and those were superior to DESS arthrograms. These differences were statistically significant. Discussion

Table 3. Quantitative evaluation of non-enhanced studies (n = 20): means and standard deviations. s CNR rc standardized to time CNR (subacromial fat vs rotator cuff); n CNR rc non-standardized CNR (subacromial fat vs rotator cuff) Mean FISP DESS SE

sCNR rc (SD)

n CNR rc (SD)

0.75 (0.39) 0.62 (0.37) 1.36 (0.58)

7.5 (3.9) 8.4 (5.1) 24.7 (10.6)

Table 4. Quantitative evaluation of non-enhanced studies (n = 20): t -tests p -value a

FISP vs DESS FISP vs SEa DESS vs SEb a b

s CNR rc

n CNR rc

0.1836 < 0.0001 < 0.0001

0.3881 < 0.0001 < 0.0001

Unpaired t -test paired t -test

Spin-echo images performed worse than the FISP arthrograms, but better than the DESS arthrograms. The differences between FISP and DESS arthrograms, as well as the difference between SE and the DESS images, were statistically highly significant. Only borderline significance was found between the FISP and SE arthrograms. The t -test for non-standardized CNR had the same significances with the exception of CNR in subacromial fat vs intra-articular contrast in FISP and SE arthrograms (p = 0.62). The results of the non-enhanced control group are shown in Tables 3 and 4. There was no significant difference between non-standardized FISP and DESS arthro-

Magnetic resonance arthrography of the glenohumeral joints has been described by several authors [1–5]. It may play a role with regard to exact delineation of partial and full-thickness tears as well as in the differential diagnosis between partial rotator cuff tears vs tendinopathy and partial vs small full-thickness tears [2]. The exact therapeutic technique either using arthroscopy or open surgery may depend on such detailed diagnosis [7]. Most investigators have used intra-articular gadopentetate for MR arthrography. However, this contrast medium is not registered for intra-articular use in the United States and in other countries. Due to high cost, potential legal problems and limited range of indications, manufacturers of contrast media are reluctant to seek registration. Therefore, radiologists as well as national registration boards are interested in the assessment of alternatives. Saline is especially attractive due to its availability, low cost and absence of adverse reactions. However, T2-weighted images are required in order to obtain sufficient contrast [6, 8]. This should no longer be a major problem due to the availability of fast (turbo) SE sequences which allow to obtain both shorter imaging times and to increase the number of excitations and, secondarily, to improve CNR. There is also an increasing number of GE sequences with potential T2-weighting such as the DESS sequence used in this investigation. The initial reason to prefer DESS images to turbo SE images were theoretical advantages such as the possibility to obtain contiguous thin slices in a short imaging time and previous practical experiences with joint imaging. The use of another, T2*-weighted GE sequence has been proven to be adequate for shoulder images [9]. Employing fat-suppressed T2-weighted SE images represent another option to improve contrast using saline as intra-articular contrast medium. However, this type

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Table 5. Qualitative evaluation: means and ranges Sequence

N

Rotator cuff

Labrum

Borders

Motion artefacts

Total score

DESS SE FISP

34 14 26

1.9 (0–3) 0.8 (0–2) 2.9 (2–3)

0.7 (0–1) 0.7 (0–1) 1 (1–1)

1.9 (1–3) 2.1 (1–3) 2.2 (1–3)

2.4 (2–3) 1.4 (0–3) 2.4 (1–3)

7 (4–9) 5 (1–7) 8.5 (7–10)

Table 6. Qualitative evaluation: statistical test Z corrected for ties (p for two-tailed test) a

DESS vs FISP SE vs FISPa DESS vs SEb a b

Rotator cuff

Labrum

Borders

Motion artefacts

Total score

− 4.1 (< 0.0001) − 5.7 (< 0.0001) − 3.2 (0.002)

− 2.8 (0.005) − 2.8 (0.004) − 1.4 (0.2)

− 1.7 (0.09) − 0.5 (0.6) − 0.7 (0.5)

− 0.3 (0.7) − 3.0 (0.002) − 2.7 (0.007)

− 4.1 (< 0.0001) − 5.1 (< 0.001) − 3.1 (0.002)

Mann-Whitney U -test Wilcoxon signed-rank test, only 14 shoulders with both SE and DESS images

of sequence commonly did not result in satisfactory images using our equipment due to severe signal inhomogeneity. During the course of our investigation, the DESS sequence appeared to be less reliable than anticipated in our early experience. Contrast between intra-articular fluid and the normal as well as abnormal rotator cuff appeared to be especially weak which made the differentiation between degeneration and tears difficult. This later proved to be true using formal quantitative and qualitative assessment of the rotator cuff. The quantitative assessment of the DESS sequence as used in the present investigation may underestimate the value of this sequence, because occasionally an artefact of unknown origin was present which caused central hypointensity of fluid (Fig. 5). Due to the low SIs within the ROI placed in the axillary recess, contrast between fluid and the rotator cuff may occasionally have been underestimated. The FISP arthrograms were superior in nearly every respect to DESS arthrograms. They were also superior to SE arthrograms in most aspects. However, our study design did not take into account other potentially important abnormalities of the glenohumeral joint. For instance, the presence of fluid within the subacromial bursa is a predictor of joint abnormalities [10]. Small amounts of such fluid are best seen using T2-weighted SE images. One drawback of the present investigation is the small number of surgically proven diagnoses. Surgery had been performed in 3 and arthroscopy in 4 of our 60 patients between MR imaging and preparation of this paper. Therefore, we were not able to measure CNR between proved torn and intact (but degenerated) parts of the rotator cuff. Based on our results, saline arthrograms in combination with DESS and SE sequences are inferior to arthrograms with diluted gadopentetate and a FISP sequence,

both using standardized CNR and a qualitative scoring. Further studies have to prove that these quantitative and qualitative differences have an influence on the accuracy of MR arthrography. References 1. Flannigan B, Kursunoglu-Brahme S, Snyder S, Karzel R, Del Pizzo W, Resnick D (1990) MR arthrography of the shoulder: comparison with conventional MR imaging. AJR 155: 829–832 2. Hodler J, Kursunoglu-Brahme S, Snyder SJ et al. (1992) Rotator cuff disease: assessment with MR arthrography versus standard MR imaging in 36 patients with arthroscopic confirmation. Radiology 182: 431–436 3. Palmer WE, Brown JH, Rosenthal DI (1993) Rotator cuff: evaluation with fat-suppressed MR arthrography. Radiology 188: 683–687 4. Palmer WE, Brown JH, Rosenthal DI (1994) Labral-ligamentous complex of the shoulder: evaluation with MR arthrography. Radiology 190: 645–651 5. Chandnani VP, Yeager TD, Berardino T de et al. (1993) Glenoid labral tears: prospective evaluation with MR imaging, MR arthrography, and CT arthrography. AJR 161: 1229–1235 6. Hajek PD, Sartoris DJ, Neuman CH, Resnick D (1987) Potential contrast agents for MR arthrography: in vitro evaluation and practical observations. AJR 149: 97–104 7. Snyder SJ (1993) Evaluation and treatment of the rotator cuff. Orthop Clin North Am 24: 173–182 8. Tirman PFJ, Stauffer AE, Crues JV et al. (1993) Saline magnetic resonance arthrography in the evaluation of glenohumeral instability. Arthroscopy 9: 550–559 9. Tuite MJ, Yandow DR, Smet AA de, Orwin JF, Quintana FA (1994) Diagnosis of partial and complete rotator cuff tears using combined gradient-echo and spin-echo imaging. Skeletal Radiol 23: 541–546 10. Monu JUV, Pruett S, Vanarthos WJ, Pope TL (1994) Isolated subacromial bursal fluid on MRI of the shoulder in symptomatic patients: correlation with arthroscopic findings. Skeletal Radil 23: 529–534